Big Horn 4 in. x 2-1/4 in. Tapered Adapter is designed to efficiently connect your dust collection system by stepping down from a larger 4-inch main line to a smaller 2-1/4-inch branch line. The small end of this adapter ly fits the 2-1/4-inch opening on your Shop-Vac, allowing you to insert the Shop-Vac hose securely. This tapered fitting increases air velocity near your machine where it's needed most, improving dust collection performance. It connects to a standard 4-inch dust collection hose and should be fastened with a hose clamp for a secure fit. Model Number: 11448